Shroud for multiple runner fluid couplings



June 14, 1949. R. P. CLIFTON SHROU'D FOR MULTIPLE RUNNER FLUID COUPLINGS 2 Sheets-Sheet 1 Filed Dec, 12, 1945 N O T F- L C D T R E B O R June 14, 1949. R. PVCLVIFTON 2,473,131

SHROUD FOR MULTIPLE RUNNER FLUID COUPLINGS Filed Dec. 12, 1945 2 Sheets-Sheet 2 Rosgl auwom ATTORNEY Patented June 14, 19

SHROUD FOR MULTIPLE-RUNNER FL r g COUPLINGS Robert E. Clifton, Deni-born, Mich., assignor to Packard Motor Car Company. Detroit, Mich., a corporation of Michigan Application December 12, 1945, Scrial No. 634,418

7 Claims.

This invention relates to variable speed power transmission mechanism and particularly to transmissions for motor vehicles.

During recent years fluid couplings have become increasingly popular in automotive drives. When these devices are used with a conventional change-speed transmission or with an automatically shiftable gearbox, the slipping characteristic thereof permits the driver to stop without disenaging the clutch and to remain in the higher gear of the prima y ru e of t e 1 coup in ratios for practically all ordinary driving. Fig. 4a is a sectional detail of Fig. 4, as indicated Because the well known two element coupling by A-A thereon; can not multiply torque, it must be used with'some Fi 5 is a vertical section of the Fig. 4 runner; sort of change-speed gearbox. Attempts to utilize and the slipping characteristic of the coupling to af- Figs. 6 and 7 are views similar to Figs. 4 a 5, fact an automatic gear change by providing two but of the secondary runn r f the p n of driven elements, one connected to the output Fig. l. s shaft through a gearset and the other connected R rr o F 1 a 4 t0 7. it will be Seen to the output shaft directly or through a higher that my imp ve fl d coupl comprises a imratio gearset have been somewhat successful. See B a p y runner N and Secondary for example that patent to Duffield, No. 2,373,234, ru ner The p ma runner I l s'd pos d e granted April 10, 1945. tween the impeller ill and the secondary runner In transmissions such a shown by m m, t i2 and the runners are enclosed in a fluid tight impeller of the fluid coupling is rotated at engine sh m el r h van s l3 arranged ra ispeed, and a pair of runners disposed in series ally about the axis of the couplin Thes vanes with the impeller and with each other are conare preferab y formed y die casting as a i l nected respectively to the propeller shaft through u -assembly, a torus member 23 being cast ingearsets of diiierent ratio. The vehicle is started tegral th i a are provided wi tabs lo from rest in the lowest gear ratio, the first runner which are received in slots i5 formed in the houstransmltting the torque and when the torque difng member it. The tabs it are securely fastened ierence between the propeller shaft and the en- $0 the member y Staking 'p e gine shaft decreases by a predetermined amount, housing 15 adapted t e fa t ed to e engine the second runner assumes the drive in a higher r n h f no shown) and carries a gear ll ratio,a one-way clutch being provided to permit which may be engaged by the starter pinion for overrun of the gearsets. J5 starting the engine.

A disadvantage of such an arrangement lies in A h n m m r 8 is h ly e u ed to the comparatively short period of operation in the member l5 and when assembled with the enthe lower gear ratio. When driving a vehicle so gine. the housin i made fluid tight. The memequipped, one is aware of a flat spot in the 9.0- bar I6 is of relatively heavy section and together celeration run which occurs almost immediately with housing is constitutes the engine flywheel. after breakaway from rest. This is caused by the u d in ia t n w h th us n second runner of the coupling taking over the is a hub which carries the P y runner N. drive too soon and before suiiicient momentum of The latter is preferably formed as an integral die the vehicle has been attained. v casting (Figs. 4 and 5) of light metal to insure a The object of my invention is to provide an im- 15 small polar moment of inertia and is bolted to the proved fluid coupling wherein the run er ar hub '9 or otherwise attached in any suitable manconstructed and arranged such that a plurality of ner. circulating fluid circuits are set up whereby the The runner H has radial vanes 20, an outer distribution of torque between the runners may shroud 2i and an inner shroud 22. The inner be more accurately predetermined. so shroud 22 is disposed approximately opposite the More specifically, I provide an improved detorus or shroud 23 carried by the impeller such sign of coupling wherein the period of slip bethat an inner zone of fluid circulation is provided tween the runners is substantially lengthened as will be later explained. during acceleration of the vehicle when the cou Mounted coaxially with the hub I9 is another pling is used with a gearbox as described above. 65 hub 24 to which the secondary runner I2 is se- 2 In describing my invention, 1 have omitted the gearing, engine, disconnecting clutch, etc., as these parts form no part thereof. In the drawings:

Fig. l is a vertical longitudinal sectional view of one form of my improved coupling;

- Figs. 2 and 3 are similar part sectional views or modified forms of the invention;

Fig. 4 is a front elevation (partly broken away) cured. The

3 latter is also preferably formed of casting of light metal (see Figs. 8 and radial vanes 25 and an outer shroud a single die 7) and has 22.

The primary runner II is cut away around the shroud 22 in such manner that it is adapted to nest with the secondary runner 12 as can be seen in the drawing. It will be seen also that the form of the respective runners II and I2 is such that they are perfectly adapted to die 'casting technique.

As indicated in Fig. 4a, the vanes of runner II have a slight taperor draft (in the order of 1") for easy withdrawal of the article from the mold. In addition, the outer shroud 2| and the inner shroud 22 are disposed in non-overlapping relation and the arcs of these members have been chosen so that natural draft is provided and no interference to removal from the mold is provided. The vanes 25 of the runner l2 are similarly tapered and the shroud 26 extends radially outwardly from the hub, the arc thereof being considerably less than 180". Here again no interference with the mold is encountered in casting.

It will be understood that the hubs l9 and 24 are adapted to be connected by means of suitable shafts with gearsets of different ratio in a manner suggested by the aforesaid Duflleld patent.

V The coupling is filled with fluid by moving fluid to the coupling through passages formed in or between the runner shafts with a fluid reservoir for continuous replenishment of the fluid supply if desired. The plug 21 provides means for draining the coupling of fluid.

The operation of the device is as follows:

Let it be assumed that the impeller is rotated by an engine and that the two runners are com nected with the vehicle driving wheels through searsets of different ratio.

Immediately upon rotation of the impeller ll, fluid is set in motion by centrifugal force and travels radially outwardly in the passages formed by the vanes I: as indicated by the arrows. The shroud 23 directs the fluid into the passages of the primary runner i l and part of the flow travels through the primary runner passages into the passages of the secondary runner i2, while another part of the flow directed by the shroud 22, travels radially inwardly and back into the impellerpassages directly. The fluid that enters the secondary runner I2 is returned to the impeller by way of the primary runner passages at the radially innermost portions thereof.

In addition, a portion of the fluid circulates about the center of the vortex and inside the confines of both shrouds 22 and 23. The arrows on Fig. 1 clearly indicate the three distinct toroidal paths of fluidcirculation, viz.: A, from the impeller to the primary runner, to the secondary runner, thence back to the impeller through the primary runner this being radially outside of both shrouds 22 and 23: B, from the impeller to the primary runner and back to the impeller; this circuit being outside of shroud 23 and inside of shroud 22. C, from the impeller to the primary runner and back to the impeller inside of both shroud 22 and shroud 23.

It may readily be seen that the energy imparted to the fluid during its radial acceleration in the impeller passages of the respective runners in proportion to the slip and to the radial runner vane area that is subjected to the force of the fluid. In the case of the form of the invention shown in Fig. 1, the fluid will exert more force on the primary runner ll than on the secondary Astheslipofthe primary runner II with respect to the impeller ll decreases'due to acceleration of the vehicle with consequent lessening of load practically disappear and all three resistance, the energy taken from the fluid by the runner ii decreases and the runner l2receives more and more energy which tends to increase its speed and decrease the slip.

The secondary runner l2 eventually will approach the speed of the runner II and will assume the drive if connected to a higher ratio gearset, the runner ll either free-wheeling in the circuit or looking up to the runner i2 by means of an automatic clutching device (no shown). At the end of the acceleration period, slip will fluid elements will rotate at substantially equal speed.

It may thus be seen that I have provided in a multiple runner coupling an arrangement of the coupling elements which permits a relatively longer period of slip between the runners with consequent improved acceleration of the load. Fig. 2 shows a modified form of coupling wherein the primary: runner 9 provides a relatively greater vane area exposed to the fluid circuit during its radially inward travel and the secondary runner l2 has a relatively smaller vane area thus exposed. This form of coupling provides a longer intermediate speed ratio acceleratlon period than that of Fig. 1 because of the longer period of slip between the runners.

Fig. 3 shows still another modification, the vane areas of the two runners having been modified to provide a still longer acceleration period.

which of the couplings illustrated in Figs. 14% is best for a particular vehicle depends upon several factors such as the power-weight ratio, the desired acceleration characteristics, the gear ratios. etc.

The relationship between certain of the circuits established in the foregoing coupling is described and claimed in my prior application, Serial No. 588,617, filed April 16, 1945.

Having thus described for illustrative purposes preferred forms of my invention, I wish to point out that I do not intend to limit the invention in its broader aspects except as set forth in the claims below.

I claim:

1. A fluid coupling having an impeller, a primary runner and a secondary runner, a shroud carried by the impeller; shrouds carried by the runners, said shrouds being disposed in cooperative relation such that upon rotation of the impeller a plurality of fluid circulating circuits are provided, one of said circuits disposed radially outside said impeller shroud and including only the impeller and the primary runner.

2. A fluid coupling having an impeller, a primary runner and a secondary runner, a shroud carried by the impeller; shrouds carried by the runners, said shrouds being disposed in cooperative relation such that upon rotation of the impeller a plurality of fluid circulating circuits are provided, one of said circuits disposed radially outside said impeller shroud and including only the impeller and the primary runner, and another of said circuits disposed peller shroud and including onl th impeller and the primary runner.

3. .A fluid coupling having an impeller, a primary runner and a secondary runner, a shroud carried by the impeller; shrouds carried by the radially inside said imshroud on the impeller for defining the vortex I of the fluid circuit; an inner shroud on the primary runner arranged to cooperate with said impeller shroud such that upon rotation of the impeller a plurality of fluid circuits are provided, one within said shrouds, another outside said shrouds and a third outside of said impeller shroud but within said runner shroud.

5. A fluid coupling including an impeller memher and a pair of runner members arranged for rotation relatively to the impeller and each other, means for circulating fluid from said impeller member through said runner members and back to said impeller member, said runner members being disposed in nested relation, and means comprising shrouds on said impeller and runner members for dividing the fluid flow into a plurality of circuits, two of said circuits including one only of said runner members.

6. A runner for a fluid coupling, said runner comprising a hub, a plurality of vanes extending radially outward from said hub, and fluid directing shrouds extending across the vanes, each shroud defining a portion of diflerent sized toroida1 fluid circuits through the coupling and neither shroud overlapping the other in a radial direction.

'7. A runner for a fluid coupling, said runner comprising a hub, a plurality ofvanes extending radially outward from said hub and including portions of inner and outer toroidal fluid circuits through the coupling, shrouds extending across the ends of the vanes and defining the outer boundary of the outer toroidal fluid circult, and a second shroud extending across the sides of the vanes and defining the outer boundary of the inner toroidal circuit, neither shroud overlapping the other in a radial direction.

' ROBERT P. CLIFTON.

REFERENCES CITED v The following references are of record in the file of this patent:

UNITED STATES PATENTS 7 Date 

